OLED display panel

ABSTRACT

An OLED display panel and manufacturing method of the panel are provided in which a terminal electrode is exposed by performing etching with fixed etching conditions without performing step processing. A terminal region comprised from a plurality of metal electrodes  2  conducting with an organic light emitting element of a display part is formed above a substrate  1 . Next, a stacked sealing film comprised from a first SI contained inorganic layer, an organic resin layer and a second Si contained inorganic layer is formed above a surface of the display part and the terminal region  6 . Next, etching is performed using etching conditions suitable for the first and the second SI contained inorganic layer while the display part is masked, the first and the second SI contained inorganic layer above the metal electrode  2  are removed and a surface of the metal electrode  2  is exposed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2013-198158, filed on Sep. 25,2013, the entire contents of which are incorporated herein by reference.

FIELD

The present invention is related to an OLED display panel in which aterminal group supplied with an image signal or drive signal is formedabove a part of a substrate and a plurality of OLED (OrganicLight-Emitting Diodes) for displaying an image are formed in a matrixabove the substrate.

BACKGROUND

An OLED panel is formed form a display part comprised from a pluralityof OLED (Organic Light-Emitting Diodes) arranged in a matrix for displayan image, a circuit such as a driver for selectively driving each OLEDwhich forms the display part, and a terminal comprised from a pluralityof terminal electrodes connected to a flexible blueprint circuitsubstrate (referred to below as [FPC substrate]) for supplying an imagesignal and a drive power to a driver from the exterior. The displaypart, circuit such as the driver and terminal are formed above asubstrate made from glass or ceramics.

In this type of OLED display panel, it is necessary to form a stackedsealing film above the display part in order to improve weatherresistance of an organic light emitting layer which forms an OLED andsecure reliability. This stacked sealing layer is formed from threelayers, a SiN film, organic resin film, and SiN Film in order from theOLED side or from four layers, a SiN film, SiO film, organic resin filmand SiN film (for example, refer to Japanese Laid Open Patent2005-504652). When foreign bodies are attached to the top of a bankwhich separates OLED's or on the OLED itself, what is called a stepwisebreak is often produced so that SiN does not wrap up to a part whichbecomes a shadow of foreign objects when forming a SiN film. In thiscase, adopting a film structure in which an organic resin film issandwiched by a SiN film, because the organic resin is formed with asmooth surface shape and envelopes foreign objects, a stepwise break ofa SiN formed above thereon is prevented.

The stacked sealing film conventionally is sufficient if it is formedonly above a display apart. However, in order to simplify the filmformation process as well as secure the effects of sealing, it ispreferred that the stacked sealing film is once formed across the entiresurface of the OLED display panel. In this case, because a terminalelectrode must be exposed in order to be electrically connected with aFPC substrate, after forming a stacked sealing film, it is necessary toremove the part of the stacked sealing film formed above a terminal byetching etc.

However, the stacked sealing film described above includes a SiN filmand an organic resin film. Since the etching conditions such as the typeof process gas used for etching between a SiN film and organic resinfilm are different, in order to securely remove the stacked sealing filmfrom above a terminal, what is called step processing must be carriedout which is a process for switching the etching conditions for eachfilm to be etched. When this step processing is carried out, the processtime is increased and it becomes necessary to use more complex etchingapparatus. Therefore, yield is reduced and the cost is increased.

Therefore, the present invention attempts to provide an OLED displaypanel and manufacturing method of the panel in which a terminalelectrode is exposed by performing etching with fixed etching conditionswithout performing step processing.

SUMMARY

An OLED display panel according to the present invention includes asubstrate, a display part including a plurality of organic lightemitting elements formed above the substrate, a plurality of electrodesformed in a band shape above the substrate and each capable ofconducting with an electrode above another substrate respectively, and astacked sealing film formed above the display part and including a firstSi contained inorganic layer, an organic resin layer and a second Sicontained inorganic layer in sequence from the substrate side, whereinthe first Si contained inorganic layer and the organic resin layer areformed between the plurality of electrodes.

A manufacturing method of an OLED display panel according to the presentinvention includes forming a display part including a plurality oforganic light emitting elements above a substrate, forming a pluralityof electrodes in a band shape above the substrate, each capable ofconducting with an electrode above another substrate, forming a stackedsealing film including a first contained inorganic layer, an organicresin layer and a second contained inorganic layer in sequence from thesubstrate side above the display part and the plurality of electrodes,and exposing a surface of the plurality of electrodes by performingetching using etching conditions suitable for the first Si containedinorganic layer and the second Si contained inorganic layer while thedisplay part is masked.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a planar view diagram of an OLED display panel according to afirst embodiment;

FIG. 2 is a partial expanded cross-sectional diagram of each OLED of adisplay part;

FIG. 3 is a partial expanded vertical cross-sectional diagram of aterminal region;

FIG. 4 is a partial expanded vertical cross-sectional diagram during amanufacturing process of a terminal region;

FIG. 5 is a partial expanded vertical cross-sectional diagram during amanufacturing process of a terminal region according to a secondembodiment; and

FIG. 6 is a partial expanded vertical cross-sectional diagram of aterminal region according to the second embodiment.

DESCRIPTION OF EMBODIMENTS

The embodiments of an OLED display panel according to the presentinvention are explained below based on the drawings.

First Embodiment

First, a process where it is possible to expose a terminal electrode byperforming etching using fixed etching condition without performing stepprocessing using the present embodiment is explained. As a result ofkeen research by the inventors, a film thickness distribution isgenerated in an acryl resin without forming a uniform film when thereare uneven parts on a base coated with the resin. As a result, it wasdetermined that it is difficult to form the acryl resin on a flatsection and that there is a tendency for the resin to form a film byagglomerating exclusively in recessed parts. This tendency is assumed tobe caused by the influence of the environment which promotes molecularbonding of the acryl resin being significantly different between recessparts and flat parts. A similar tendency is also confirmed withpolyimide and phenol resin.

Therefore, in the present embodiment, an acryl resin film is used as anorganic resin film sandwiched between SI contained inorganic films. Theupper surface of each terminal electrode which forms a terminal is flatand both sides form a recess part. As a result, it is difficult to formthe acryl film on an upper surface of each terminal and an acryl filmcoated on a terminal flows into a recess part between terminalelectrodes form the surface of the terminal electrode and agglomerateswithin the recess part. As a result, it is possible to expose thesurface of each terminal electrode by etching using etching conditionsfor the Si contained inorganic film.

Next, the structure of the OLED display panel according to the presentembodiment is explained based on FIG. 1 to FIG. 3. FIG. 1 is a planarview diagram of an OLED display panel 100 according to the presentembodiment. FIG. 2 is an expanded partial vertical cross-sectionaldiagram near each OLED which form a display part 5 of the OLED displaypanel 100. FIG. 3 is an expanded partial vertical cross-sectionaldiagram near each terminal electrode 2 of the OLED display panel 100.

As is shown in FIG. 1, in a planar view, a plurality of groups of fourOLED's 15 which display one color pixel by emitting three prime colors(red, green, blue) and white are arranged in a matrix shape at thecenter of the OLED display panel 100. These OLED's 15 are formed with adisplay area 5 which display an image by selectively adjusting an amountof emitted light and being driven. In addition, driving circuits (Xdriver, Y driver shifter register etc) 3, 4 for selectively adjusting anamount of emitted light and driving each OLED 15 within the display area5 are arranged at three locations in a periphery region of the displayarea 5 on an upper surface of the OLED display panel 100.

The display area 5 and each driving circuit 3, 4 are formed above asingle glass substrate 11. In addition, as is shown in the expandedpartial vertical cross-sectional view in FIG. 3, a plurality of wiringpatterns 10 are formed by a polysilicon thin film in the vicinity of anedge near the driving circuit 3 in the glass substrate 11. The wiringpattern 10 conducts with each driving circuit and is arranged forconnecting to ground as well as supplying a power supply voltage and adrive voltage to each driving circuit 3, 4. An end part of each wire islinked with metal electrode 2. The metal electrode 2 is formed in astrip shape in a length direction in a direction which intersects anedge near the glass substrate 11. In addition, each metal electrode 2 isformed as a terminal region 6 which is connected to a flexible printcircuit substrate (FPC substrate) 7 which supplies drive power, adriving signal and an earth potential from the exterior by beingarranged along the edge described above in the glass substrate 11.Furthermore, as is shown in the expanded partial verticalcross-sectional view in FIG. 3, each metal electrode 2 includes astructure in which an ITO (Indium Tin Oxide) film 13 is coated on asurface of a TAT (Titan Aluminum Titan) layer 12. The TAT layer 12 maybe formed together when a source wire 21, drain wire 22 and anode 23described below are formed. In addition, the ITO thin film 13 may beformed together when a transparent cathode 26 described below is formed.This is for improving conductivity between an electrode on the side ofthe FPC substrate 7 and the wiring pattern 10. In addition, a siliconnitride (SiN) layer 8 and silica (SiO) layer 9 which remain when a bankdescribed below is produced are arranged between each metal electrode 2.Each metal electrode 2, silicon nitride (SiN) layer 8 and silica (SiO)layer 9 are separated and form a recess part. In addition, the wiringpattern 10 described above is exposed on the bottom of this recess part.The ITO thin film 13 described above is connected to the wiring pattern10 exposed on the bottom of the recess part. Furthermore, the ITO thinfilm 13 reaches beyond the recess part and as far as the edge of thesilicon nitride (SiN) layer 8 and silica (SiO) layer 9.

In addition, as is shown in FIG. 2, the display part is broadlycomprised from a TFT (Thin Film Transistor) layer 14 and an OLED layer15. The main structural components of the TFT layer 14 are a firstinsulation layer 16, semiconductor layer 17, second insulation layer 18,third insulation layer 19, gate wire (gate electrode) 20, a pair ofwires (source wire 21, drain wire 22) and an anode 23. The firstinsulation layer 16 is formed on an upper surface of the glass substrate11. The semiconductor layer 17 is patterned and formed above theinsulation layer 16. The second insulation layer 18 is formed to coverthe semiconductor layer 17. The gate wire 20 is formed above and belowthe semiconductor layer 17 sandwiching the second insulation layer 18.The third insulation layer 19 may be a planarized layer covering thegate wire 20. A pair of wires are patterned above the third insulationlayer 19 and are connected to the semiconductor layer 17 via a contacthole formed in the third insulation layer 19. The anode 23 is formed inthe drain wire 22 so as to have a shape corresponding to each pixel. Theanode 23 may also be a reflection electrode. Furthermore, instead of theglass substrate 11, a ceramic, resin or metal substrate may be used or aflexible substrate.

The main structural components of the OLED 15 are a bank 24, an organicEL layer 25, a transparent cathode 26 and a stacked sealing film 27. Thebank 24 is formed between adjacent pixels and while covering an end partof the anode 23, exposes parts other than this end part and define alight emitting region. The organic EL layer 25 is formed above the anode23 and includes a similar shape to the anode 23. Furthermore, theorganic EL layer 25 may be formed so as to cover the anode 23 and bank24. The transparent cathode 26 is formed on an upper surface of theorganic EL layer 25 and bank 24. The stacked sealing film 27 is formedso as to cover the transparent cathode 26. The organic EL layer 25 is aseparated-function type and applies a stacked structure of a positivehole injection layer 25 a, a positive hole transport layer 25 b, a lightemitting layer 25 c, an electron transport layer 25 d and an electroninjection layer 25 e in sequence from the anode 23 side. In addition, afield-effect transistor (gate wire (gate electrode), 20, semiconductor17, source wire 21, drain wire 22) is driven according to a signalapplied to the gate wire 20. In response to driving the field-effecttransistor, holes supplied from the anode 23 and electrons supplied fromthe transparent cathode 27 each reach the light emitting layer 25 c viathe positive hole injection layer 25 a and positive hole transport layer25 b and the electron injection layer 25 e and electron transport layer25 d, and light is emitted when they recombine within the light emittinglayer 25 c.

Furthermore, although the stacked sealing film 27 actually includes athree layer structure comprised form a first SiN contained inorganicfilm, an acryl resin film and a second SiN contained inorganic film inthis order form the side of the transparent cathode 26, only a singlelayer is depicted in FIG. 2 for the purposes of creating the diagrams.In addition, the stacked sealing film 27 covers the entire surface ofthe OLED display panel 100 including the formation parts of the displayarea 5 and formation parts of each driving circuit 2, 4 described aboveexcept the terminal region 6.

When the manufacturing process of the OLED display panel 100 formed asdescribed above is explained, first, the TFT layer 14 is formed using ausual LPTS (Low Temperature Poly-Silicon) process. Although polysiliconis used as the material of the semiconductor 17 of the TFT layer 14,amorphous silicon may be used, an oxide semiconductor or an organicsemiconductor may also be used. Furthermore, a polysilicon thin film asthe wiring pattern described above is also formed in the formationlocation of the terminal region 6 by the formation process of the TFTlayer 14.

Next, a bank which defines each light emitting region by covering anedge of the anode 23 separated for each light emitting region of eachcolor of each pixel of the TFT layer 14 is formed by silicon nitride(SiN) and silica (SiO). That is, a silicon nitride (SiN) film and silica(SiO) film are formed on the entire surface of the glass substrate wherethe TFT layer 14 is formed. Following this, an aperture is arrange din alocation corresponding to each light emitting region by etching thesefilms, the anode 23 is exposed, the formation location of each metalelectrode 2 of the terminal region 6 is opened and the wiring pattern 10of the polysilicon thin film is exposed. Furthermore, an organic resinfilm may be used for the bank.

Next, an organic EL layer 25 is formed in each aperture corresponding toeach light emitting region. It is possible to use high-molecularprinting, an inkjet, laser transfer or deposition when forming theorganic EL layer 25.

Next, the cathode 26 which supplies electrons to the organic EL layer 25of each OLED 15 is formed from a single transparent electrode across anentire surface of the display area 5 which includes all organic ELlayers 25 (electron injection layer 25 e) and banks formed in each lightemitting region.

Next, in order to improve moisture resistance, prevent water permeationand improve the causes of obstacles to reliability such as DS (darkspots), the stacked sealing film 27 is arranged above the cathode 26across the entire surface of the OLED panel including the display area 5and terminal region 6. Specifically, the stacked sealing film 27 isformed from a total of three layers, the first Si contained inorganicfilm 28, an organic resin film 30 and a second Si contained inorganicfilm 31 in sequence from the side of the cathode. Although a SiN filmwhich is an fine inorganic material film is used for each Si containedinorganic film 28, 31, a SiO₂ film or N contained SiO film may also beused. The thickness of the Si contained inorganic film 28, 31 ispreferred to be 200˜600 nm for example and the thickness of the organicresin film 30 is preferred to be 200˜800 nm. For the reasons describedabove, acryl, polyimide or phenol resin is used as the organic resinfilm 30. As a result, the organic resin film 30 is formed so as to beburied in a recess part formed in the surface of the first Si containedinorganic film 28 formed according to the shape of a base but is notformed on a flat surface of the first Si contained inorganic film 28.Therefore, in the terminal region 6, the first Si contained inorganicfilm 28 is formed according to the shape of the surface of the metalelectrode 2 and a stacked film (silicon nitride (SiN) film 8 and silica(SiO) film 9) and an inner surface of a the recess part, and a recesspart in the first Si contained inorganic film 28, that is, a material ofthe organic resin film 30 agglomerates in the recess part formed betweenthe metal electrode 2 and the stacked film (silicon nitride (SiN) film 8and silica film (SiO) film 9) and the recess part becomes buried.Therefore, the surface of the organic resin film formed in the recesspart and the exposed surface of the first Si contained inorganic film 28become a single surface and above this, the second Si containedinorganic film 31 is formed almost flat. FIG. 4 shows this state.

Next, from this state, dry etching is performed once on the first SIcontained inorganic film 28 and the second Si contained inorganic film31 while parts other than the terminal region 6 are masked. Becausegases such as SF₆ and O₂ are used in this etching and the etchingconditions are suitable for an inorganic film, the organic resin film 30remains unchanged without being etched. Then, with the organic resinfilm remaining, the entire surface area of the metal electrode 2 isexposed as is shown in FIG. 3, and at almost the same time, the surfaceof the SiO film 9 is also exposed. In the present embodiment, the OLEDdisplay panel is considered completed in this state, and when the OLEDdisplay panel is incorporated into a final product, an FPC substrate 7overlaps the terminal region 6 and each metal electrode 2 of theterminal region 6 conducts with an electrode of the FPC substrate 7. Atthis time, any remaining organic resin film 30 and first Si containedinorganic film 28 covered by the organic resin film 30 does notnegatively affect conduction of the terminals.

In this way, even in the case where a stacked sealing film including anorganic resin film, first Si contained inorganic film and second Sicontained inorganic film is adopted, the stacked resin film above anelectrode is removed without performing a step processing by performingetching once according to etching conditions suitable for a first Sicontained inorganic film and second Si contained inorganic film, and itis possible to expose an electrode surface.

According to the OLED display panel and manufacturing method of thepanel of the present embodiment explained above, because an etchingprocess of the organic resin film 30 and first Si contained inorganicfilm 28 of the parts covered by the organic resin film 30 is removed, aswell as contributing to process simplification, full etching time of theorganic resin film 30 which requires a long time due to a large filmthickness distribution can be omitted and it is possible to realize areduction takt time. For example, when the organic resin film 30 isformed to a thickness of 250 nm using acryl, the thickness of theorganic resin film 30 which agglomerates in the recess parts between themetal electrode 2 and the stacked film (the silicon nitride (SiN) layer8 and silica (SiO) layer 9) is about 800 nm. Therefore, if full etchingis performed on the organic resin film 30, a takt time of about threetimes the time required for etching to 200 nm is required. Furthermore,if the first Si contained inorganic film 28 covered by the organic resinfilm 30 is removed by etching, coverage of the silicon nitride (SiN)layer 8 and silica (SiO) layer 9 by the ITO thin film 13 becomes poor,and a problem occurs whereby an etching gas side etches the siliconnitride (SiN) layer 8 and silica (SiO) layer 9. According to the presentembodiment, because this side etching does not occur, there is fear ofnegative effects on reliability. As a result, because stable manufactureis possible according to the present embodiment, yield can be improvedand it is possible to realize a cheaper product manufacture.

Second Embodiment

In the second embodiment, compared to the first embodiment describedabove, a SiO film or an amorphous silicon film 29 is formed between thefirst Si contained inorganic film 28 and the organic resin film 30.

FIG. 5 shows the state where a stacked sealing film 27′ is formed abovethe OLED display panel 100 in the second embodiment. Specifically, thestacked sealing film 27′ is formed from a total of four layers, thefirst Si contained inorganic film 28, a SiO film or amorphous siliconfilm 29, the organic resin film 30 and the second Si contained inorganicfilm 31 in sequence from the side of the cathode 26. The SiO film oramorphous silicon film 29 is formed evenly on a surface of the first Sicontained inorganic film 28 and also on an inner surface of the recessparts between the metal electrode 2 and the stacked film (the siliconnitride (SiN) layer 8 and silica (SiO) layer 9). Therefore, the organicresin film 30 agglomerates above the SiO film or amorphous silicon film29 in the recess part.

FIG. 6 shows the completed state of an OLED display panel with thesurface of the metal electrode 2 exposed in the present embodiment. Dryetching is performed once on the first Si contained inorganic film 28,SiO film 29 and second Si contained inorganic film 31 while parts otherthan the terminal region 6 are masked in FIG. 5. In this way, the firstSi contained inorganic film 28, SiO film or amorphous silicon film 29and second Si contained inorganic film 31 formed above the metalelectrode 2 and above the SiO layer 9 are removed, and the second Sicontained inorganic film 31 formed above the organic resin film 30 isremoved. In this completed state, the SiO film or amorphous silicon film29 as well the organic resin film 30 and first Si contained inorganicfilm 28 remain in the recess parts between the metal electrode 2 and thestacked film (the silicon nitride (SiN) layer 8 and silica (SiO) layer9).

Because the other structure and effects of the second embodiment areexactly the same as those in the first embodiment described above, theirexplanation is omitted.

Modified Example

In the embodiments described above, although an anode was used asreflection electrode and a cathode as a transparent electrode forforming what is called a top emission type OLED display panel, in thecase of forming what is called a bottom emission type OLED displaypanel, an anode may be used as a transparent electrode and a cathode asa reflection electrode. In addition, it is possible to form a film inthe order ITO/Ag/ITO as the structure of a reflection electrode and itis possible to use ITO or IZO (Indium Zinc Oxide) as a transparentelectrode.

In addition, because what is called a top emission type OLED displaypanel is formed in the embodiments described above, an opposingsubstrate is arranged and a filler agent such as an epoxy resin isfilled between the substrates. In this case, because it is possible toarrange a color filter on an inner surface of a sealing substrate, it ispossible to make all of the emitted colors of the organic light emittinglayer 25 c of each OLED 15 white.

What is claimed is:
 1. An OLED display panel comprising: a substrate; adisplay part including a plurality of organic light emitting elementsformed above the substrate; a plurality of electrodes formed in a bandshape above the substrate and each capable of conducting with anelectrode above another substrate respectively; and a stacked sealingfilm formed above the display part and including a first Si containedinorganic layer, an organic resin layer and a second Si containedinorganic layer in sequence from the substrate side; wherein the firstSi contained inorganic layer and the organic resin layer are formedbetween the plurality of electrodes.
 2. The OLED display panel accordingto claim 1, wherein a SIO layer is formed between the first Si containedinorganic layer and the organic resin layer.
 3. The OLED display panelaccording to claim 1, wherein an amorphous silicon layer is formedbetween the first Si contained inorganic layer and the organic resinlayer.
 4. The OLED display panel according to claim 1, wherein in thedisplay part, a layer with same material as a bank sectioning eachorganic light emitting element is formed between the plurality ofelectrodes, and the first Si contained inorganic layer and the organicresin layer the same as the stacked sealing film are formed between thelayer having the same material as the bank and each electrode.
 5. TheOLED display panel according to claim 4, wherein wiring conducting withan organic light emitting element forming the display part is formedabove the substrate, and an ITO thin film is formed across a surface ofthe electrode and a surface of the wiring.
 6. The OLED display panelaccording to claim 5, wherein the ITO thin film extends up to a surfaceof the layer having the same material as the bank sectioning eachorganic light emitting element.